/* dualview.c -- bit fields and bitwise operators */
#include <stdio.h>
#include <stdbool.h>
#include <limits.h>
/* BIT-FIELD CONSTANTS */
/* line styles    */
#define SOLID   0
#define DOTTED  1
#define DASHED  2
/* primary colors */
#define BLUE    4
#define GREEN   2
#define RED     1
/* mixed colors   */
#define BLACK   0
#define YELLOW  (RED | GREEN)
#define MAGENTA (RED | BLUE)
#define CYAN    (GREEN | BLUE)
#define WHITE   (RED | GREEN | BLUE)

/* BITWISE CONSTANTS   */
#define OPAQUE			0x1
#define FILL_BLUE		0x8
#define FILL_GREEN		0x4
#define FILL_RED		0x2
#define FILL_MASK		0xE
#define BORDER			0x100
#define BORDER_BLUE		0x800
#define BORDER_GREEN	0x400
#define BORDER_RED		0x200
#define BORDER_MASK		0xE00
#define B_SOLID			0
#define B_DOTTED		0x1000
#define B_DASHED		0x2000
#define STYLE_MASK		0x3000

const char * colors[8] = { "black", "red", "green", "yellow",
	"blue", "magenta", "cyan", "white" };

struct box_props {
	bool opaque					: 1;
	unsigned int fill_color		: 3;
	unsigned int				: 4;
	bool show_border			: 1;
	unsigned int border_color	: 3;
	unsigned int border_style	: 2;
	unsigned int				: 2;
};

void show_settings(const struct box_props * pb);

union Views		/* look at data as struct or as unsigned short */
{
	struct box_props st_view;
	unsigned short us_view;
};

void show_settings(const struct box_props * pb);
void show_settings1(unsigned short);
char * itobs(int n, char * ps);

int main(void)
{
	/* create Views object, initialize struct box view */
	union Views box = {{true, YELLOW, true, GREEN, DASHED}};
	char bin_str[8 * sizeof(unsigned int) + 1];

	printf("Original box settings:\n");
	show_settings(&box.st_view);
	printf("\nBox settings using unsigned int view:\n");
	show_settings1(box.us_view);

	printf("bits are %s\n",
			itobs(box.us_view, bin_str));
	box.us_view &= ~FILL_MASK;			/* clear fill bits */
	box.us_view |= (FILL_BLUE | FILL_GREEN); /* reset fill */
	box.us_view ^= OPAQUE;				 /* toggle opacity */
	box.us_view |= BORDER_RED;			 /* wrong approach */
	box.us_view &= ~STYLE_MASK;		   /* clear style bits */
	box.us_view |= B_DOTTED;		/* set style to dotted */

	printf("\nModified box settings:\n");
	show_settings(&box.st_view);
	printf("\nBox settings using unsigned int view:\n");
	show_settings1(box.us_view);
	printf("bits are %s\n",
			itobs(box.us_view, bin_str));

	return 0;
}

void show_settings(const struct box_props * pb)
{
	printf("Box is %s.\n",
		pb->opaque == true ? "opaque" : "transparent");
	printf("The fill color is %s.\n", colors[pb->fill_color]);
	printf("Border %s.\n",
		pb->show_border == true ? "shown" : "not shown");
	printf("The border color is %s.\n", colors[pb->border_color]);
	printf("The border style is ");
	switch (pb->border_style)
	{
		case SOLID  : printf("solid.\n"); break;
		case DOTTED : printf("dotted.\n"); break;
		case DASHED : printf("dashed.\n"); break;
		default     : printf("unknown type.\n");
	}
}

void show_settings1(unsigned short us)
{
	printf("box is %s.\n",
		(us & OPAQUE) == OPAQUE ? "opaque" : "transparent");
	printf("The fill color is %s.\n",
		colors[(us >> 1) & 07]);
	printf("Border %s.\n",
		(us & BORDER) == BORDER ? "shown" : "not shown");
	printf("The border style is ");
	switch (us & STYLE_MASK)
	{
		case B_SOLID  : printf("solid.\n"); break;
		case B_DOTTED : printf("dotted.\n"); break;
		case B_DASHED : printf("dashed.\n"); break;
		default       : printf("unknown type.\n");
	}
	printf("The border color is %s.\n",
			colors[(us >> 9) & 07]);

}
char * itobs(int n, char * ps)
{
	int i;
	const static int size = CHAR_BIT * sizeof(int);

	for (i = size - 1; i >= 0; i--, n >>= 1)
		ps[i] = (01 & n) + '0';
	ps[size] = '\0';

	return ps;
}